The Ordovician strata of the Ennedi Plateau, northeastern Chad (Erdi Basin)

The Ennedi Massif, a UNESCO World Heritage Site in northeastern Chad, preserves a critical record of Early to Middle Ordovician flooding events and the end-Ordovician glaciation. This study reveals that the Lower Sandstones, characterized by fluvial-dominated deposits with NW to NNE paleocurrent trends, were interrupted by high-frequency marine incursions marked by tidal deposits and ichnofacies such as Cruziana and Arthrophycus. Above an erosional unconformity, evidence of glaciation is documented through fluvioglacial conglomeratic deposits, which are overlain by the fine-grained Bedo Formation. The latter contains glaciomarine deposits at its base and possibly extends into the Lower Silurian in its upper part, onlapping an exhumed erosion surface with north-trending glacial lineations. This research provides insights into the paleogeographic dynamics of the Gondwana platform during a pivotal period of Earth's history.

Ghienne, J.-F., Moussa, A., Saad, A., Djatibeye, B., & Youssouf, H. M. (2023). The Ordovician strata of the Ennedi Plateau, northeastern Chad (Erdi Basin). Comptes Rendus. Géoscience, 355(G1), 63–84. https://doi.org/10.5802/crgeos.180